Pulses of the lower limb

There are 4 arterial pulses which are routinely felt in the lower limb.

1. femoral
2. popliteal
3. posterior tibial
4. dosalis pedis (dorsum of foot)

In clinical practice, the pulses in the lower limb are taken with the patient lying face upwards and relaxed on a bed or examination couch in a warm room. It is conventional for the person examining to stand on the right of the patient. The technique of feeling the pulse through the skin is known as 'palpating' the pulse; arterial pulses are palpated by gentle finger pressure over the artery with the pulps (pads) of the index and middle fingers. The fingers are placed across the line of the artery. When palpating a pulse you may not feel it at first. Concentrate all your attention on what you are feeling, it often helps to close your eyes.

During this tutorial, where possible, you will be instructed to find the particular pulse on your own body. This may be difficult to do whilst sitting at the computer, so stand or move appropriately. Also some confusion may arise from being able to feel your own pulse in your fingers. Taking the pulse of a patient in clinical practice may require a different technique and this will be described.

Femoral pulse

Most of the blood supply to the lower limb is carried in the external iliac artery. This becomes the femoral artery as it enters the thigh by passing deep to the inguinal ligament at the groin. In the femoral triangle of the upper thigh, the femoral artery has a major branch; the profunda femoris artery which supplies much of the thigh.

Locate the superior border of the pubis in the mid line of the body; this is the uppermost part of the pubic symphysis. Feel the anterior limit of the iliac crest. The femoral pulse can be found midway between these two bony points (the mid-inguinal point)

Sometimes samples of arterial blood are taken from the femoral artery. The needle is passed into the artery 2-3 cm below the mid-inguinal point to ensure that the peritoneal cavity and intestines are not pierced.

Popliteal pulse

	The femoral artery leaves the femoral triangle and runs through the adductor canal. Having passed along the adductor canal, the femoral artery enters the popliteal fossa by passing through the adductor magnus muscle. The name of the vessel then changes to the popliteal artery.

The popliteal pulse is particularly hard to palpate on your own limb. If you are sitting next to someone who will volunteer you could attempt to palpate the pulse in the following manner. Ask your volunteer to raise their leg up onto a chair and relax their leg fully whilst you support it. Gently clasp the sides of the knee and press the pulps of all your fingers into the popliteal fossa.The popliteal pulse is deeply placed and is thus diffuse in character and less distinctly felt.

In clinical practice you would use the following technique. Ask the subject to bend the knee so that it is flexed to about 90 degrees. Sit on the right hand edge of the bed close to the subject right foot. As before gently clasp the sides of the knee (of either limb) and press the pulps of your fingers into the popliteal fossa.

Dorsalis pedis pulse

Below the level of the knee joint, the popliteal artery divides into the anterior and posterior tibial arteries.The anterior branch enters the anterior compartment of the leg by passing between the tibia and fibula above the interosseous membrane. It supplies the structures in the anterior compartment of the leg and continues onto the dorsum of the foot as the dorsalis pedis artery, which finally enters the sole of the foot by passing between the first and second metatarsals.

Place your fingers half way down the dorsum of the foot on the bony area in the line between the first and second toes. The bones you can feel are the dorsal aspect of the navicular and the intermediate cuneiform bones. The pulse is palpated where the artery passes over this area.

The anterior tibial artery is also palpable, it is felt anterior to the ankle joint, midway between the malleoli. It is not usually included in the clinical examination, because dosalis pedis is more readily appreciated.

Posterior tibial pulse

The posterior tibial artery continues through the calf, lying between the soleus and the deeper muscles and giving off the peroneal artery, which enters the lateral compartment. It then enters the sole of the foot by passing behind the medial malleolus. In the sole it divides into the medial and lateral plantar arteries which anastomose (join) with each other and with the dorsalis pedis artery to supply the anterior foot and toes.

Locate the medial malleolus. 2-3cm below and behind it you should find the posterior tibial pulse. when taking the pulse on your own foot it is easier to use the thumb. In clinical practice the pulse is palpated using the pulps of the index and middle fingers. The artery is slightly deeper placed than the dorsalis pedis and therefore more concentration is often required to feel its pulsations.

Palpation of the pulses forms an important part of the assessment of the arterial blood supply of the lower limb. In clinical practice, this assessment may give clues about a compromised circulation, e.g.intermittent claudication, a condition of the leg caused by atheroma (blockage) of the arteries. In this condition pain in the lower limb(s) develops during walking and is relieved by rest. A patient with intermittent claudication may have weak or absent pulses in the lower limb. On examination the limb may be cold to the touch and cyanosed (blue) and there may be local hair loss. Gentle pressure on the toes may lead to prolonged skin blanching.

In medical practice, when admitting a patient it is important to palpate the dorsalis pedis and posterior tibial pulses in both limbs and, if absent, the popliteal and femoral pulses. The presence or absence of these pulses should be recorded carefully in the patient notes. It is not uncommon for disease processes to result in emboli (blood clots in vessels) which can suddenly block arteries and require medical or surgical intervention. If accurate records are made then it is easy to detect a change in peripheral pulses should a blockage occur.

Limb pulses are often helpful to a clinician when treating a seriously injured patient. It avoids interference with the head, neck and thorax which may be involved in the injury and undergoing treatment by other clinicians, thus making them inaccessible.

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